Many Common Pathogens are Present in the Operative Room Air During Surgery.

BACKGROUND: The main objective of this study was to assess the sanitary measures of operating theaters using next-generation sequencing. METHODS: Air was sampled from the operating room for the whole duration of 10 surgical days of "clean" (no infection cases) procedures (6 hip/knee arthroplasty and 4 spine cases). Controls consisted of samples at the beginning of the day (1 hour before the surgery started) and at the end of the day after terminal cleaning. One additional control sample, consisting of a culture swab that was opened and exposed to the air for 5 seconds, was collected at each time point. All samples were sent for next-generation sequencing analysis (16S rRNA sequencing) for bacterial identification. RESULTS: Overall, 306 samples were collected (159 controls and 147 experimental). Microbial DNA was detected in only 1 control sample, while 18 (12.2%) experimental samples were positive for microbial DNA. The most common organisms retrieved were Escherichia coli (6/18, 30%), Cutibacterium acnes (3/18, 15%), and Pseudomonas aeruginosa (2/18, 11.1%). There was no difference in positive samples between arthroplasty and spine cases (P > .05). CONCLUSION: Microbial organisms are not uncommonly present in the operating room air during hip and knee arthroplasties and spine procedures.

Positive Cultures Can Be Safely Ignored in Revision Arthroplasty Patients That Do Not Meet the 2018 International Consensus Meeting Criteria.

BACKGROUND: During aseptic revision total joint arthroplasty (TJA), one or more cultures may occasionally isolate an organism. The hypothesis of this study was that in a portion of patients undergoing revision arthroplasty for aseptic failure, culture may isolate an organism(s) that can be left untreated. METHODS: All patients undergoing revision TJA from 2000 to 2017 at two institutions were retrospectively reviewed. Patients were categorized as aseptic if they were appropriately investigated preoperatively and did not meet the 2018 International Consensus Meeting criteria. In the aseptic revision cohort, patients with a single positive culture or multiple cultures positive for different organisms ("organism-positive") and patients who had negative intraoperative cultures ("organism-negative") were compared based on demographics, comorbidities, operative details, subsequent reoperations, and periprosthetic joint infection (PJI). RESULTS: In total, 3,234 International Consensus Meeting-negative aseptic revision TJAs were included, of which 215 patients (6.6%) were organism-positive, 196 (91.2%) had a single positive culture, and 19 (8.8%) were positive for 2 or more distinct organisms (ie, polymicrobial). The most prevalent organisms were coagulase-negative Staphylococci (37.5%), Staphylococcus epidermidis (9.6%), and Cutibacterium acnes (8.0%). Demographics and operative details were comparable between the groups. Using multiple regressions there was no association between culture positivity and the rate of reoperation or PJI. CONCLUSION: Isolation of organisms by culture in patients undergoing revision for aseptic failure was not uncommon. As long as these patients were appropriately investigated preoperatively and PJI was excluded, these findings suggest that culture results may be ignored without subjecting patients to additional antimicrobial treatment.

Emergence of Antibiotic Resistance Across Two-Stage Revision for Periprosthetic Joint Infection.

BACKGROUND: The current preferred treatment for chronic hip and knee periprosthetic joint infection (PJI) involves both surgical intervention and antibiotic treatment as part of a two-stage revision. The purpose of this study is to determine how often patients who underwent a two-stage revision for chronic PJI developed a subsequent antibiotic-resistant infection. METHODS: We retrospectively reviewed the clinical records of 142 patients who underwent a two-stage revision for a chronic culture-positive PJI from January 2014 to May 2019. Demographic data and risk factors for PJI were identified. Resistance was defined in accordance with microbiology laboratory report and minimum inhibitory concentration. Statistical analysis consisted of descriptive statistics and univariate analysis. RESULTS: Only 10 of the 142 patients (7.04%) demonstrated emergence of resistance to antibiotics across their two-stage revision. At reimplantation, 25 (17.6%) patients had positive cultures. Of these, 16 patients presented with a novel organism and 9 patients had positive culture for the same organism as the initial infection. During the entire course of the two-stage revision, including spacer exchanges and irrigation and debridement procedures, 15 (10.56%) patients demonstrated persistent infections, whereas 25 (17.6%) patients presented with novel infections. 26 (18.3%) patients had reinfection of the same joint within one year. CONCLUSION: In the given cohort, there does not appear to be a major emergence of antibiotic resistant organisms in patients undergoing two-stage exchange arthroplasty and antibiotic treatment.

Low-Dose Aspirin Administered for Venous Thromboembolism Prophylaxis Reduces the Incidence of Heterotopic Ossification in Total Joint Arthroplasty.

BACKGROUND: Heterotopic ossification (HO) is a common complication following total joint arthroplasty (TJA). However, the pathophysiology of HO is not entirely understood. Inflammation may play a significant role in the pathogenesis of HO as nonsteroidal anti-inflammatory drugs are effective in the prevention of HO. The purpose of this study is to examine if aspirin (ASA), when used as venous thromboembolism (VTE) prophylaxis, influenced the rate of HO formation following TJA. METHODS: We queried our longitudinally maintained database to identify all patients who underwent primary total hip arthroplasty (THA) or total knee arthroplasty (TKA) for osteoarthritis between January 2016 and June 2018 with at least 3-month radiographic follow-up. In total, 1238 THAs and 1051 TKAs were included for analysis. Radiographs were reviewed and HO formation graded according to the Brooker classification. Patient demographic and VTE prophylaxis data were collected and reviewed for accuracy. Univariate and multivariate analysis was performed to evaluate the effect of ASA on HO formation. RESULTS: The overall rate of HO was 37.5% after THA and 17.4% after TKA. Patients receiving ASA were less likely to develop HO after THA (34.8% vs 45.5%; P < .001), as well as HO after TKA (13.4% vs 18.4%; P = .047) compared to patients receiving non-ASA VTE prophylaxis. The rate of HO formation trended to be lower, albeit not statistically significantly, in patients receiving low-dose ASA (81 mg) vs high-dose ASA (325 mg). CONCLUSION: Patients undergoing primary TJA receiving ASA for VTE prophylaxis were less likely to develop HO compared to patients who were administered non-ASA VTE prophylaxis.

Association of Perioperative Red Blood Cell Transfusion With Symptomatic Venous Thromboembolism Following Total Hip and Knee Arthroplasty.

BACKGROUND: Prior registry data suggest that perioperative red blood cell (RBC) transfusion may increase the incidence of venous thromboembolism (VTE) in patients status post surgery. However, there are limited data that explore VTE risk after perioperative transfusion in the setting of primary total joint arthroplasty (TJA). Our aim is to investigate the association between perioperative RBC transfusion and the development of symptomatic VTE after adjusting for confounding variables. METHODS: We retrospectively reviewed all patients undergoing primary TJA at a single institution from 2001 to 2016. The primary outcome was development of symptomatic VTE (deep vein thrombosis or pulmonary embolism) up to 90 days following primary TJA. To identify the association between RBC transfusion and development of VTE, univariate and multivariate analyses were used, as well as a sensitivity analysis using propensity score matching based on patient comorbidities. RESULTS: Of the 29,003 patients who underwent TJA, 2500 (8.62%) received RBC transfusion perioperatively and 302 (1.04%) developed a postoperative VTE within 90 days of surgery. While univariate analysis did suggest a slightly increased incidence of VTE in association with RBC transfusion (odds ratio [OR], 1.53; 95% confidence interval [CI], 1.09-2.16), this difference was eliminated when multivariate analysis (OR, 0.42; 95% CI, 0.12-1.39) and propensity score matching (propensity-matched OR, 1.2; 95% CI, 0.7-1.8) were employed. CONCLUSION: Perioperative RBC transfusion does not significantly increase the incidence of symptomatic VTE following primary TJA in the 90-day postoperative period after adjustment for host VTE risk scores and other confounding variables. Perioperative RBC transfusion may be safely administered if indicated following total hip and knee arthroplasty.

Direct Anterior Approach to the Hip Does Not Increase the Risk for Subsequent Periprosthetic Joint Infection.

BACKGROUND: Recent studies suggest an increased risk for periprosthetic joint infection (PJI) utilizing the direct anterior (DA) approach to the hip. The purpose of this study was to investigate whether such an increased risk does indeed exist on a large cohort of patients, operated by experienced surgeons and taking into account various confounders. METHODS: This was a single institutional study, including all patients who underwent primary total hip arthroplasty during the last decade, who were operated on by four high-volume arthroplasty surgeons utilizing a single surgical approach. Three of them utilized the direct lateral (DL) approach while one of them used the DA approach throughout the entire study. Patient characteristics, demographics, and comorbidities were assessed as well as operative and perioperative factors and their association with PJI. Association between surgical approach and PJI was evaluated in a univariate followed by a multivariate regression analysis. RESULTS: A total of 10,201 patients were included in the study. Of those, 4390 (43.0%) underwent total hip arthroplasty through the DA approach and 5811 (57.0%) through the DL approach. PJI rates were 0.9% (38/4390) in the DA group compared with 1.3% (73/5811) in the DL group (P = .068). Results from a regression analysis showed no significant association between PJI and DA approach (adjusted odds ratio 0.760, 95% confidence interval 0.428-1.348, P = .348). The risk remained nonsignificant in patients with higher body mass index. There were also no significant differences in the infecting organisms between the two groups. CONCLUSION: The DA approach to the hip does not increase the risk for subsequent PJI.

Novel in vivo mouse model of shoulder implant infection.

BACKGROUND: Animal models are used to guide management of periprosthetic implant infections. No adequate model exists for periprosthetic shoulder infections, and clinicians thus have no preclinical tools to assess potential therapeutics. We hypothesize that it is possible to establish a mouse model of shoulder implant infection (SII) that allows noninvasive, longitudinal tracking of biofilm and host response through in vivo optical imaging. The model may then be employed to validate a targeting probe (1D9-680) with clinical translation potential for diagnosing infection and image-guided débridement. METHODS: A surgical implant was press-fit into the proximal humerus of c57BL/6J mice and inoculated with 2 µL of 1 × 103 (e3), or 1 × 104 (e4), colony-forming units (CFUs) of bioluminescent Staphylococcus aureus Xen-36. The control group received 2 µL sterile saline. Bacterial activity was monitored in vivo over 42 days, directly (bioluminescence) and indirectly (targeting probe). Weekly radiographs assessed implant loosening. CFU harvests, confocal microscopy, and histology were performed. RESULTS: Both inoculated groups established chronic infections. CFUs on postoperative day (POD) 42 were increased in the infected groups compared with the sterile group (P < .001). By POD 14, osteolysis was visualized in both infected groups. The e4 group developed catastrophic bone destruction by POD 42. The e3 group maintained a congruent shoulder joint. Targeting probes helped to visualize low-grade infections via fluorescence. DISCUSSION: Given bone destruction in the e4 group, a longitudinal, noninvasive mouse model of SII and chronic osteolysis was produced using e3 of S aureus Xen-36, mimicking clinical presentations of chronic SII. CONCLUSION: The development of this model provides a foundation to study new therapeutics, interventions, and host modifications.

The Microbiome of Osteoarthritic Hip and Knee Joints: A Prospective Multicenter Investigation.

BACKGROUND: Recent advances in high-throughput DNA sequencing technologies have made it possible to characterize the microbial profile in anatomical sites previously assumed to be sterile. We used this approach to explore the microbial composition within joints of osteoarthritic patients. METHODS: This prospective multicenter study recruited 113 patients undergoing hip or knee arthroplasty between 2017 and 2019. Demographics and prior intra-articular injections were noted. Matched synovial fluid, tissue, and swab specimens were obtained and shipped to a centralized laboratory for testing. Following DNA extraction, microbial 16S-rRNA sequencing was performed. RESULTS: Comparisons of paired specimens indicated that each was a comparable measure for microbiological sampling of the joint. Swab specimens were modestly different in bacterial composition from synovial fluid and tissue. The 5 most abundant genera were Escherichia, Cutibacterium, Staphylococcus, Acinetobacter, and Pseudomonas. Although sample size varied, the hospital of origin explained a significant portion (18.5%) of the variance in the microbial composition of the joint, and corticosteroid injection within 6 months before arthroplasty was associated with elevated abundance of several lineages. CONCLUSIONS: The findings revealed that prior intra-articular injection and the operative hospital environment may influence the microbial composition of the joint. Furthermore, the most common species observed in this study were not among the most common in previous skin microbiome studies, suggesting that the microbial profiles detected are not likely explained solely by skin contamination. Further research is needed to determine the relationship between the hospital and a "closed" microbiome environment. These findings contribute to establishing the baseline microbial signal and identifying contributing variables in the osteoarthritic joint, which will be valuable as a comparator in the contexts of infection and long-term arthroplasty success. LEVEL OF EVIDENCE: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Melatonin Does Not Improve Sleep Quality in a Randomized Placebo-controlled Trial After Primary Total Joint Arthroplasty.

INTRODUCTION: Sleep disturbance is a common concern among patients who have undergone total joint arthroplasty (TJA). Poor sleep during the postoperative period affect quality of life directly and may influence pain recovery after TJA. The purpose of this prospective study was to investigate whether the daily use of exogenous melatonin for 6 weeks after TJA can mitigate the effects of TJA on sleep. METHODS: A cohort of 118 patients undergoing primary total hip arthroplasty or total knee arthroplasty from 2018 to 2020 were randomized to melatonin (6 mg) or placebo for 42 days after surgery. Inclusion criterion was patients undergoing unilateral primary TJA. Patients who underwent bilateral TJA and revision TJA, with a history of sleep disturbance, and on opioid medication or sleep aids preoperatively were excluded. Sleep quality was assessed at baseline and at 2 and 6 weeks postoperatively using the validated self-administered questionnaire, Pittsburgh Sleep Quality Index (PSQI). Continuous and categorical variables were analyzed using Student t-test and chi-square analysis, respectively. Multivariate linear regression analysis was also conducted. RESULTS: Patients in both groups exhibited higher PSQI scores, representing lower sleep quality, at both 2 and 6 weeks postoperatively compared with that at baseline. Overall, global PSQI scores were 6.8, 9.8, and 8.8 at baseline, week 2, and week 6, respectively. No significant differences were noted between melatonin and placebo groups at baseline (6.8 versus 6.8, P = 0.988), week 2 (10.2 versus 9.3, P = 0.309), or week 6 (8.8 versus 8.7, P = 0.928). In multivariable regression, the only significant predictors of increased PSQI scores were an elevated baseline PSQI score (at both time points), a decreased length of stay (at week 2 only), and patients undergoing total hip arthroplasty versus total knee arthroplasty (at week 6 only). CONCLUSION: Patients undergoing TJA had poor sleep quality both preoperatively and postoperatively. The use of exogenous melatonin did not demonstrate any notable effect on sleep quality.

Fracture-Associated Microbiome and Persistent Nonunion: Next-Generation Sequencing Reveals New Findings.

INTRODUCTION: Fracture nonunion remains a devastating complication and may occur for several reasons, though the microbial contribution remains poorly estimated. Next-generation sequencing (NGS) techniques, including 16S rRNA gene profiling, are capable of rapid bacterial detection within clinical specimens. Nonunion cases may harbor microbes that escape detection by conventional culture methods that contribute to persistence. Our aim was to investigate the application of NGS pathogen detection to nonunion diagnosis. METHODS: In this prospective multicenter study, samples were collected from 54 patients undergoing open surgical intervention for preexisting long-bone nonunion (n = 37) and control patients undergoing fixation of an acute fracture (n = 17). Intraoperative specimens were sent for dual culture and 16S rRNA gene-based microbial profiling. Patients were followed for evidence of fracture healing, whereas patients not healed at follow-up were considered persistent nonunion. Comparative analyses aimed to determine whether microbial NGS diagnostics could discriminate between nounions that healed during follow-up versus persistent nonunion. RESULTS: Positive NGS detection was significantly correlated with persistent nonunion, positive in 77% more cases than traditional culture. Nonunion cases were observed to have significantly increased diversity and altered bacterial profiles from control cases. DISCUSSION: NGS seems to be a useful adjunct in identification of organisms that may contribute to nonunion. Our findings suggest that the fracture-associated microbiome may be a significant risk factor for persistent nonunion. Ongoing work aims to determine the clinical implications of isolated organisms detected by sequencing and to identify robust microbial predictors of nonunion outcomes. LEVEL OF EVIDENCE: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

In vitro and in vivo methods to study bacterial colonization of hydrogel dermal fillers.

Preclinical in vitro and in vivo methods to study bacterial interactions with dermal fillers and infection pathogenesis are lacking. In this work, first in vitro methods to assess protein biofouling and effective pore size of commercial dermal fillers, including degradable hyaluronic acid (HA)-based fillers and other semi-degradable or permanent fillers (non-HA), were developed. The results were then related to Staphylococcus aureus (S. aureus) adhesion rates in vitro. HA fillers had less protein sorption than non-HA fillers and overall had smaller effective pore sizes. The properties correlated with levels of bacterial adhesion, where the control glass surface had the most rapid increase in bacterial cell adhesion, with a slope of 0.29 cm-2  min-1 , three unique non-HA fillers had intermediate adhesion with slopes of 0.11 and 0.06 cm-2  min-1 , and three unique HA fillers had the least adhesion with slopes of 0.02, 0.02, and 0.01 cm-2  min-1 . S. aureus had greater motility on the HA fillers than on non-HA fillers. Next, a mouse model for dermal filler biofilm and infection was developed. Mice were inoculated with a controlled amount of bioluminescent bacteria (Xen36 S. aureus) and polyacrylamide hydrogels of different stiffness were injected. In vivo bioluminescence was monitored longitudinally for 35 days to ensure that lasting colonization was established. The inoculum was optimized to achieve adequate bioluminescent signal, and bacterial bioburden over time and inter-animal variability in bioburden were determined. These in vitro and in vivo approaches can be used for future studies of antimicrobial interventions for dermal fillers.

An Enhanced Understanding of Culture-Negative Periprosthetic Joint Infection with Next-Generation Sequencing: A Multicenter Study.

BACKGROUND: The challenges of culture-negative periprosthetic joint infection (PJI) have led to the emergence of molecular methods of pathogen identification, including next-generation sequencing (NGS). While its increased sensitivity compared with traditional culture techniques is well documented, it is not fully known which organisms could be expected to be detected with use of NGS. The aim of this study was to describe the NGS profile of culture-negative PJI. METHODS: Patients undergoing revision hip or knee arthroplasty from June 2016 to August 2020 at 14 institutions were prospectively recruited. Patients meeting International Consensus Meeting (ICM) criteria for PJI were included in this study. Intraoperative samples were obtained and concurrently sent for both routine culture and NGS. Patients for whom NGS was positive and standard culture was negative were included in our analysis. RESULTS: The overall cohort included 301 patients who met the ICM criteria for PJI. Of these patients, 85 (28.2%) were culture-negative. A pathogen could be identified by NGS in 56 (65.9%) of these culture-negative patients. Seventeen species were identified as common based on a study-wide incidence threshold of 5%. NGS revealed a polymicrobial infection in 91.1% of culture-negative PJI cases, with the set of common species contributing to 82.4% of polymicrobial profiles. Escherichia coli, Cutibacterium acnes, Staphylococcus epidermidis, and Staphylococcus aureus ranked highest in terms of incidence and study-wide mean relative abundance and were most frequently the dominant organism when occurring in polymicrobial infections. CONCLUSIONS: NGS provides a more comprehensive picture of the microbial profile of infection that is often missed by traditional culture. Examining the profile of PJI in a multicenter cohort using NGS, this study demonstrated that approximately two-thirds of culture-negative PJIs had identifiable opportunistically pathogenic organisms, and furthermore, the majority of infections were polymicrobial. LEVEL OF EVIDENCE: Diagnostic Level II . See Instructions for Authors for a complete description of levels of evidence.

Alpha-defensin does not provide additional benefit over leukocyte esterase in the diagnosis of periprosthetic joint infection.

Background: Leukocyte esterase (LE) and α-defensin (AD) are two synovial biomarkers that are used for the diagnosis of periprosthetic joint infection (PJI), however, the superiority of one over the other remains unknown. We aimed to compare their diagnostic value.Methods: In this retrospective study, we evaluated patients who underwent revision total hip and knee arthroplasty at a single institution between 2013 and 2019 for whom both LE and AD were available. PJI was defined by the 2018 International Consensus Meeting criteria. The diagnostic performance of AD and LE was compared.Results: Overall, 122 patients (28 PJI and 94 aseptic revisions) were included. The area under the curve was 0.905 (95% confidence interval[CI]:0.820-0.991) and 0.913 [95%CI:0.834-0.992] for LE and AD, respectively. Positive and negative predictive values were 95.8% (95%CI:76.5%-99.4%) and 94.9% (95%CI:89.4%-97.6%) for LE and 89.0% (95%CI:72.2%-96.1%) and 96.0% (95%CI:90.5%-98.3%) for AD. While both tests were useful in 18 cases that were inconclusive based on preoperative findings, AD had no benefit over LE.Conclusion: Both LE and AD are valuable markers in patients with suspected PJI. Since LE is very inexpensive and readily available point-of-care test, we believe it offers more value in the work up of suspected PJI.

Opioid Use Following Inpatient Versus Outpatient Total Joint Arthroplasty.

BACKGROUND: Although the risks of continued opioid use following inpatient total joint arthroplasty (TJA) have been well-studied, these risks in the outpatient setting are not well known. The purpose of the present study was to characterize opioid use following outpatient compared with inpatient TJA. METHODS: In this retrospective cohort study, opioid-naïve patients who underwent inpatient or outpatient (no overnight stay) primary, elective TJA from 2007 to 2017 were identified within a large national commercial-claims insurance database. For inclusion in the study, patients had to have been continuously enrolled in the database for ≥12 months prior to and ≥6 months after the TJA procedure. Multivariable analyses controlling for demographics, geography, procedure, year, and comorbidities were utilized to determine the association between surgical setting and risk of persistent opioid use, defined as the patient still filling new opioid prescriptions >90 days postoperatively. RESULTS: We identified a total of 92,506 opioid-naïve TJA patients, of whom 57,183 (61.8%) underwent total knee arthroplasty (TKA). Overall, 7,342 patients (7.9%) underwent an outpatient TJA procedure, including 4,194 outpatient TKAs. Outpatient TJA was associated with reduced surgical opioid prescribing (78.9% compared with 87.6% for inpatient procedures; p < 0.001). Among the 80,393 patients (86.9%) who received surgical opioids, the total amount of opioids prescribed (in morphine milligram equivalents) was similar between inpatient (median, 750; interquartile range, 450 to 1,200) and outpatient procedures (median, 750; interquartile range, 450 to 1,140; p = 0.47); however, inpatient TJA patients were significantly more likely to still be taking opioids after 90 days postoperatively (11.4% compared with 9.0% for outpatient procedures; p < 0.001). These results persisted in adjusted analysis (adjusted odds ratio, 1.13; 95% confidence interval, 1.03 to 1.24; p = 0.01). CONCLUSIONS: Outpatient TJA patients who received opioid prescriptions were prescribed a similar amount of opioids as those undergoing inpatient TJA procedures, but were significantly less likely to become persistent opioid users, even when controlling for patient factors. Outpatient TJA, as compared with inpatient TJA, does not appear to be a risk factor for new opioid dependence, and these findings support the continued transition to the outpatient-TJA model for lower-risk patients. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Comparative meta-omics for identifying pathogens associated with prosthetic joint infection.

Prosthetic joint infections (PJI) are economically and personally costly, and their incidence has been increasing in the United States. Herein, we compared 16S rRNA amplicon sequencing (16S), shotgun metagenomics (MG) and metatranscriptomics (MT) in identifying pathogens causing PJI. Samples were collected from 30 patients, including 10 patients undergoing revision arthroplasty for infection, 10 patients receiving revision for aseptic failure, and 10 patients undergoing primary total joint arthroplasty. Synovial fluid and peripheral blood samples from the patients were obtained at time of surgery. Analysis revealed distinct microbial communities between primary, aseptic, and infected samples using MG, MT, (PERMANOVA p = 0.001), and 16S sequencing (PERMANOVA p < 0.01). MG and MT had higher concordance with culture (83%) compared to 0% concordance of 16S results. Supervised learning methods revealed MT datasets most clearly differentiated infected, primary, and aseptic sample groups. MT data also revealed more antibiotic resistance genes, with improved concordance results compared to MG. These data suggest that a differential and underlying microbial ecology exists within uninfected and infected joints. This study represents the first application of RNA-based sequencing (MT). Further work on larger cohorts will provide opportunities to employ deep learning approaches to improve accuracy, predictive power, and clinical utility.

Point-of-care antimicrobial coating protects orthopaedic implants from bacterial challenge.

Implant related infections are the most common cause of joint arthroplasty failure, requiring revision surgeries and a new implant, resulting in a cost of $8.6 billion annually. To address this problem, we created a class of coating technology that is applied in the operating room, in a procedure that takes less than 10 min, and can incorporate any desired antibiotic. Our coating technology uses an in situ coupling reaction of branched poly(ethylene glycol) and poly(allyl mercaptan) (PEG-PAM) polymers to generate an amphiphilic polymeric coating. We show in vivo efficacy in preventing implant infection in both post-arthroplasty infection and post-spinal surgery infection mouse models. Our technology displays efficacy with or without systemic antibiotics, the standard of care. Our coating technology is applied in a clinically relevant time frame, does not require modification of implant manufacturing process, and does not change the implant shelf life.

Randomized Trial of a Virtual Reality Tool to Teach Surgical Technique for Tibial Shaft Fracture Intramedullary Nailing.

INTRODUCTION: Active learning methods have accumulated popularity due to improved results in knowledge acquisition as opposed to passive learning methods. For surgical resident physicians with limited training opportunities outside of the operating room due to time constraints, virtual reality (VR) is a relatively inexpensive and time-efficient active training method for procurement of surgical skills. We conducted a simulated intramedullary nailing (IMN) of a tibia to demonstrate VR training programs as a more effective modality of learning orthopedic surgical techniques compared to passive learning tools such as a standard guide (SG) through trained novice medical students performing a SawBones simulation of intramedullary nail fixation. MATERIALS AND METHODS: First and second-year medical students without prior experience of procedure were recruited and randomized to SG or VR training. Participants were observed performing simulated tibia IMN procedure immediately after training and evaluated by a blinded attending surgeon using procedure-specific checklist and 5-point global assessment scale. Participants returned after 2-weeks for repeat training and evaluation. RESULTS: 20 participants were recruited and randomized into VR (n = 10) and SG (n = 10) groups. All 20 participants completed the first phase and 17 completed the second phase of the study. Aggregate global assessment scores were significantly higher for VR than SG group (17.5 vs. 7.5, p < 0.001), including scores in all individual categories. The percentage of steps completed correctly was significantly higher in the VR group compared to the SG group (63% vs. 25%, p < 0.002). Average improvement between the first and second phases of the study were higher in the VR group compared to SG group across all 5-categories of the global assessment scale, and significantly higher for knowledge of instruments (50% vs. 11%, p, 0.01). DISCUSSION: VR training was more effective than a passive SG in our model of simulated tibia IMN for novice medical students. Virtual reality training may be a useful method to augment orthopedic education.

Evading the host response: Staphylococcus "hiding" in cortical bone canalicular system causes increased bacterial burden.

Extremity reconstruction surgery is increasingly performed rather than amputation for patients with large-segment pathologic bone loss. Debate persists as to the optimal void filler for this "limb salvage" surgery, whether metal or allograft bone. Clinicians focus on optimizing important functional gains for patients, and the risk of devastating implant infection has been thought to be similar regardless of implant material. Recent insights into infection pathophysiology are challenging this equipoise, however, with both basic science data suggesting a novel mechanism of infection of Staphylococcus aureus (the most common infecting agent) into the host lacunar-canaliculi network, and also clinical data revealing a higher rate of infection of allograft over metal. The current translational study was therefore developed to bridge the gap between these insights in a longitudinal murine model of infection of allograft bone and metal. Real-time Staphylococci infection characteristics were quantified in cortical bone vs metal, and both microarchitecture of host implant and presence of host immune response were assessed. An orders-of-magnitude higher bacterial burden was established in cortical allograft bone over both metal and cancellous bone. The establishment of immune-evading microabscesses was confirmed in both cortical allograft haversian canal and the submicron canaliculi network in an additional model of mouse femur bone infection. These study results reveal a mechanism by which Staphylococci evasion of host immunity is possible, contributing to elevated risks of infection in cortical bone. The presence of this local infection reservoir imparts massive clinical implications that may alter the current paradigm of osteomyelitis and bulk allograft infection treatment.

A Comparison of Defense and Plaintiff Expert Witnesses in Orthopaedic Surgery Malpractice Litigation.

BACKGROUND: According to the American Academy of Orthopaedic Surgeons (AAOS) Standards of Professionalism, the responsible testimony of expert witnesses in orthopaedic surgery malpractice lawsuits is important to the public interest. However, these expert witnesses are recruited and compensated without established standards, and their testimony can potentially sway court opinion, with substantial consequences. The objective of this study was to characterize defense and plaintiff expert orthopaedic surgeon witnesses in orthopaedic surgery malpractice litigation. METHODS: Utilizing the WestlawNext legal database, defense and plaintiff expert witnesses involved in orthopaedic surgery malpractice lawsuits from 2013 to 2017 were identified. Each witness's subspecialty, mean years of experience, involvement in academic or private practice, fellowship training, and scholarly impact, as measured by the Hirsch index (h-index), were determined through a query of professional profiles, the Scopus database, and a PubMed search. Statistical comparisons were made for each parameter among defense and plaintiff expert witnesses. RESULTS: Between 2013 and 2017, 306 expert medical witnesses for orthopaedic cases were identified; 174 (56.9%) testified on behalf of the plaintiff, and 132 (43.1%) testified on behalf of the defense. Orthopaedic surgeons who identified themselves as general orthopaedists comprised the largest share of expert witnesses on both the plaintiff (n = 61) and defense (n = 25) sides. The plaintiff witnesses averaged 36 years of experience versus 31 years for the defense witnesses (p < 0.001); 26% of the plaintiff witnesses held an academic position versus 43% of the defense witnesses (p = 0.013). Defense witnesses exhibited a higher proportion of fellowship training in comparison to plaintiff expert witnesses (80.5% versus 64.5%, respectively, p = 0.003). The h-index for the plaintiff group was 6.6 versus 9.1 for the defense group (p = 0.04). Two witnesses testified for both the plaintiff and defense sides. CONCLUSIONS: Defense expert witnesses held higher rates of academic appointments and exhibited greater scholarly impact than their plaintiff counterparts, with both sides averaging >30 years of experience. These data collectively show that there are differences in characteristics between plaintiff and defense witnesses. Additional study is needed to illuminate the etiology of these differences.

How long should we follow patients after apparently curative parathyroidectomy?

BACKGROUND: Little is known about the long-term recurrence risk for primary hyperparathyroidism after immediately "curative" parathyroidectomy. This study aimed to evaluate the risk of recurrent hyperparathyroidism in the 10 years after operation. METHOD: We retrospectively identified patients with sporadic primary hyperparathyroidism undergoing initial parathyroidectomy between November 1, 2000 and June 30, 2005. Recurrence was defined as serum calcium >10.2 mg/dL after 6 months from operation. Kaplan-Meier estimates and Cox proportional hazards were used to evaluate disease-free survival and predictors of recurrence. RESULTS: We evaluated 196 patients with a 14.8% 10-year recurrence rate. Median time to recurrence was 6.3 years (interquartile range 3.4-10.8 years), and 34.5% of all recurrences were identified >10 years after operation. There was no difference in recurrence between open and minimally invasive operation (P = .448). Double adenomas (P = .006), intraoperative parathyroid hormone drop <70% (P = .015), and young age (P = .032) were predictive of disease recurrence. Multivariable analysis demonstrated that older age was protective against recurrence (hazard ratio 0.97, 95% confidence interval 0.94-0.99, P = .034), while double adenomas (hazard ratio 3.52, 95% confidence interval 1.23-10.08, P = .019) were an independent predictor for recurrence. CONCLUSION: The long-term recurrence rate for sporadic primary hyperparathyroidism after "curative" parathyroidectomy is likely greater than reported. With over one-third of our institutional recurrences at >10 years after the initial operation, long-term follow-up is essential.